This invention relates to an apparatus for providing uniform illumination to a surface during the electronic imaging/optical scanning process, particularly a surface having information contained thereon in either a code or alphanumeric format.
Electronic imaging/optical scanning devices were developed to electronically recreate an image of the surface of an object. The electronic image is created by holding the imaging/scanning device directly over the surface to be imaged/scanned. Typically, appropriate lensing focuses the image on a CCD array. The image is converted to electronic data. The electronic data is then stored or transmitted to an appropriate data processing apparatus.
To expedite the processing of routine information, electronic imaging/optical scanning devices are used to retrieve data or information printed on or affixed to the surface of an object in code or alphanumeric format. A common example is a bar code label affixed to the surface of a package. The bar code label contains information about the package's origin, destination, order number, and the like. To retrieve the information from the bar code label, an electronic imaging/optical scanning device electronically creates a digitized image of the bar code label and transfers that image to a processing computer. The processing computer then deciphers the desired information from the digitized image. Electronic imaging/optical scanning devices can be either machine mounted or hand-held. Portable hand-held devices are especially useful when processing is required at remote locations.
The ability to retrieve data or information from the surface of an object depends largely on the quality of the digital image obtained by the electronic imaging/optical scanning device. Glare, shadows and non-uniformity in illumination on the surface during the imaging/scanning process can result in degradation of the digital image. A poor digital image can lead to loss of data. Uniform illumination over a surface is especially important when reading information on an alphanumeric label or in a two-dimensional encoded format. For example, it may be desired to obtain an electronic image of an address label for transmission to optical character recognition devices.
Known electronic imaging/optical scanning devices seek to reduce non-uniformity in illumination by using an internal light source in conjunction with a series of mirrors or reflectors. Such devices, as represented by the patents discussed below, use internally mounted mirrors or reflectors to redirect or concentrate the light generated by the internal light source onto the target surface. The redirected or concentrated light is therefor sufficient to illuminate the target surface and strong enough to overwhelm and block out ambient light during the imaging or scanning process.
Examples of these various electronic imaging/optical scanning devices include U.S. Pat. No. 3,216,317 entitled "Transposition Device and Document Processor in Character Sensing," issued to Nail on Nov. 9, 1965; U.S. Pat. No. 4,335,302 entitled "Bar Code Scanner Using Non-Coherent Light Source," issued to Robillard on Jun. 12, 1982; U.S. Pat. No. 4,603,976 entitled "Optical Mark Recognition Apparatus," issued to Fetzer, et al. on Aug. 5, 1986; U.S. Pat. No. 4,739,159 entitled "Optical Read Out Apparatus Using a Roof Mirror Lens Array," issued to Inokuchi on Apr. 19, 1988; U.S. Pat. No. 5,046,159 entitled "Image Transmitting Element and Process For Producing Same," issued to Hamanaka on Sep. 3, 1991; and U.S. Pat. No. 5,081,343 entitled "Instant Portable Bar Code Reader," issued to Chadima, Jr., et al. on Jan. 14, 1992. These patents all disclose the use of internally mounted light sources where light is redirected or concentrated onto the target surface by use of internally mounted mirrors or reflectors. U.S. Pat. No. 5,046,159 discloses the use of a transparent substrate with multiple photo-transmissible holes for receiving light energy, and U.S. Pat. No. 5,081,343 discloses the use of a flash lamp light source.
None of these patents, however, provide an apparatus for uniformly illuminating a target surface. By redirecting or concentrating light onto the target surface through mirrors or reflectors, these devices can frequently produce glare and/or shadows on the surface resulting in loss of data during the electronic imaging/optical scanning process.
Accordingly it is an object of this invention to provide an electronic imaging/optical scanning device lighting source that provides uniform illumination across the surface to be imaged or scanned.
Further objects and advantages of the invention will become apparent from the detailed description of a preferred embodiment set forth below.